1) The phenomenon known as "black holes" occurs when matter is crushed into an infinitely small space, creating a gravitational pull so strong that nothing can escape.

2) The Cricket World Cup is held every four years and features teams from around the world competing for the prestigious title.

3) The shortest scheduled commercial flight lasts just 1.7 miles and connects two Scottish islands, Westray and Papa Westray.

4) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.